3.13.11-ckt22 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
commit 7cbeed9bce7580479bb97457dad220cb3594b875 upstream.
Current permission check assumes that RSVD bit in PFEC is always zero,
however, it is not true since MMIO #PF will use it to quickly identify
MMIO access
Fix it by clearing the bit if walking guest page table is needed
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[ kamal: backport to 3.13-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.h | 2 ++
arch/x86/kvm/paging_tmpl.h | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 2926152..9b4f12a 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -113,6 +113,8 @@ static inline bool is_write_protection(struct kvm_vcpu *vcpu)
static inline bool permission_fault(struct kvm_mmu *mmu, unsigned pte_access,
unsigned pfec)
{
+ WARN_ON(pfec & PFERR_RSVD_MASK);
+
return (mmu->permissions[pfec >> 1] >> pte_access) & 1;
}
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index cba218a..90c4570 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -706,6 +706,13 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
mmu_is_nested(vcpu));
if (likely(r != RET_MMIO_PF_INVALID))
return r;
+
+ /*
+ * page fault with PFEC.RSVD = 1 is caused by shadow
+ * page fault, should not be used to walk guest page
+ * table.
+ */
+ error_code &= ~PFERR_RSVD_MASK;
};
r = mmu_topup_memory_caches(vcpu);
--
1.9.1
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